Forty-two years after the deadliest prison uprising in American history, all of the facts about what happened still most likely remain in the state’s locked files. Attorney General Eric Schneiderman needs to finally make good on his vow to unlock the truth — the whole truth.

The families of the 43 people killed, and New Yorkers, in general, are as thirsty for all the facts as they were in the above picture taken at the Capitol in Albany on Sept. 23, 1971, days after the uprising.

To Schneiderman’s credit, last spring he vowed to ask a New York Supreme Court to release two of three volumes of a major report on the riot prepared by Supreme Court Justice Bernard Meyer and sealed in 1981. The missing volumes include grand jury testimony that was collected in an investigation launched to ensure there was no corruption involved in the initial probe by the state police.

But Schneiderman and Gov. Andrew Cuomo, who prior to Schneiderman’s commitment got the ball rolling by telling the Editorial Board last spring that he’d look into releasing the documents, must not stop with the Meyer report. There is a trove of records in the state’s possession that should be made public. All of it is linked to the uprising, which resulted in the death of 10 hostages and 29 inmates when troopers stormed the prison.

For instance, there’s believed to be at least 90 boxes of records from the McKay Commission, which conducted the initial investigation of the riot parallel to one led by the state attorney general’s office. There are also grand jury and attorney general records that have been locked away for decades.

Suspicions about the state’s culpability in the bloodbath have lingered long enough. Cuomo, who talked a lot about transparency during his 2008 campaign for governor, must rattle cages again as he did last spring to free the facts.

For years, survivors of the riot’s victims have gathered at the prison to remember their loved ones as they did earlier this month. Each year, looks of uncertainty and anguish on their faces grow more intense. They’ve suffered long enough.

Information can ease their trauma. It can also provide guideposts that can help avert such a bloodbath from ever happening again. Cuomo and Schneiderman must see to it.